Receiver for use in wireless telegraphy.



No. 796,800. PATENTED AUG. 8, 1905. E. BRANLY. RECEIVER FOR USE INWIRELESS TELEGRAPHY.

APPLIOATION FILED SEPT. 4. 1902.

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No. 796,800. PATENTED AUG. 8, 1905.

' E. BRANLY.

RECEIVER FOR USE IN wIEELEss TELEGRAPHY.

APPLICATION FILED SEPT. 4. 1902.

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UNITED STATES PATENT OFFICE.

EDOUARD BRANLY, OF PARIS, FRANCE, ASSIGNOR TO VICTOR POPP, OF PARIS,FRANCE.

RECEIVER FOR USE IN WIRELESS TELEGRAPHY.

Specification of Letters Patent.

Patented Aug. 8, 1905.

Application filed September 4,1902. Serial No. 122,060.

10 all whom it may concern:

Be it known that I, EDOUARD BRANLY, of 3 Rue Boursault, in the city ofParis, Republic of France, have invented an Improved Receiver for Use inWireless Telegraphy, of which the following is a full, clear, and exactdescription.

This invention has for its object a system of receiver for electricwaves specially adapted for application in wireless telegraphy.

My receiver essentially comprises two metallic parts in contact, one ofwhich is polished and the other oxidized, the contact of the oxidizedwith the polished surface possessing the property of preventing thepassage of the current under normalconditions, but of immediatelybecoming conductive on the emission of an electric spark at a distance,and of instantly resuming its resistance under the action of a veryslight shock. One of the parts is preferably constituted of metal rods,whose blunt points are oxidized and rest upon a polished metal plate, orconversely the plate may be oxidixed and the blunt points be polished.By means of this multiple-contact device the operation of the receiveris always insured, as there will be always at least one contact capableof being rendered conductive under the'influence of electric waves.

In order that the invention may be readily understood, I haveillustrated in the accompanying drawings an example of my receiver.

Figure 1 is a diagrammatic view of the receiver. Fig. 2 is a diagramillustrating the application of the receiver. Fig. 3 shows anarrangement of apparatus based on the abovementioned principle. Fig. 4shows the coherer as mounted directly upon the recording apparatus.

The same letters of reference denote like parts in the several figures.

My receiver comprises essentially three or more rods a, of polishedsteel or other metal, having blunt points and resting upon a metal plate6, of polished steel or other metal. The three rods a are carried by aplate 0, of brass or other suitable metal provided with a binding-s'creWd, to which is attached one of the,

conducting-wires of the receiving electric circuit', of which the otherconductor is connected to plate 6. The ends of the rods a in contactwith the plate 6 are oxidized, for the purpose of creating a resistancewhich normally prevents the passage of the current of a small battery 6.The oxidation of the points of the rods may be efiected by any suitableprocess, as for example by placing them for a certain time in a hot-airstove at the proper temperature, the degree of oxidation being capableof regulation by varying the temperature of the stove and the durationof the heating. The oxidation may also be produced by chemical action.

In the circuit of the battery 6, to the poles of which the plates 0 andZ) are respectively connected, are interposed a galvanometer f and aresistance 9. The circuit being thus completed the needle of thegalvanometer f remains at zero, as the current from battery a does notflow,'the circuit being cut by the contact of the polished plate 5 withthe oxidized ends of rods a. But if a small spark be emitted at acertain distance between the two small balls of a Hertz vibrator, adeviation of the needle of the galvanometerf will immediately beobserved. The contacts of rods (0 and plate 6 therefore becomeconductive under the influence of a spark at a distance. To destroy thisconductivity and instantly restore the resistance of the contacts, it isonly necessary to impart a very slight shock to the instrument,whereupon the needle of the galvanometer f will instantly return tozero.

In the circuit of the receiver is interposed as shown in Fig. 2, a relayh, which on the passage of the current through this circuit closes thecircuit of a local battery 2' through a Morse instrument 7'.

Fig. 3 shows an apparatus arranged to work on this principle. Theapparatus comprises a base-plate 7c of insulating material, upon whichrests a conductive tray Z held in position by adjusting-screws m andcontaining a polished plate 6. Upon the base-plate 7c are mountedstandards a united by cross-bars 0, 0 having holes for the passage ofthe rods (0. The receiver is thus fixed except that the position of thepoints of contact of the rods a upon the plate 6 may be regulated bymeans of the adjusting-screws.

The decohering shock is produced by a tapper arranged in the followingmanner: Upon the upper cross-bar 0 is mounted an electromagnet 19,whereof the armature is placed in a recess in the lower cross-bar 0,this armature being connected to one end of the wire wound on the spoolsof the electromagnet. Normally the armature q rests upon aconducting-plate '1, the electromagnet p and the plate 4 being connectedrespectively with the two poles of the local battery When electric wavesare emitted at a distance the contact of rods a with plate 72 becomingconductive as hereinbefore described, the current from the small battery0 flows and the relay 7t closes the circuit of the local battery i, andoperates the Morse instrument 7, but the current also flowing throughthe electromagnet 3) its armature g which acts as a trembler imparts aslight tap or shock to the receiver, the effect of which is to instantlyrestore the resistance to the contacts and immediately render theapparatus capable of receiving another signal.

My receiver of electric waves presents great advantages resulting fromthe simplicity of its construction, and if placed in a dry situation itsefficiency is unlimited, as its restoration is in any caseinstantaneous, and moreover it possesses a high degree of sensibility.The decohering tap or shock need only be very slight, if care be takento vary the voltage of the battery to suit requirements; the motion ofthe tapper need be but of very slight extent, say halfa millimeter, forexample, hence the possibility of very rapid reception of the signalstransmitted. The effieient working of the apparatus is always assured,as of the several contact-points there would always be at least one inworking order. This regularity of working is due to the fact that thecontacts are always perfectly established and constantly in the sameconditions, the resistances present being exactly determined by thedegree of oxidation and the degree of polish of the parts in contact areconstant; conductivity is always obtained under the same influences andthe resistance is instantly restored by shocks which may be easilyproduced since the surfaces in the contact remain constantly similar.The apparatus can therefore never lose its sensibility and no externalvibration can influence it since by regulating the amount of resistanceof the contacts the shock of the coherers may itself be regulated.

In order to protect the coherer from the oxidizing action of themoistureof the air and prevent any oxidation of the poli hed surfaces, theapparatus may be placed in a chamber exhausted of air or immersed in anysuitable liquid medium such as petroleum, oil,&c., or in semiliquidfatty matter, &c., whereby the polished surfaces will be protected fromoxidation and will permanently retain their polish, whatever may be thesituation in which the apparatus is placed; thcapparatus is thus capableof working for an indefinite period.

My coherer can be mounted directly upon the recording apparatus, asshown in Fig. 4. Mounted upon the base-board j of the recorderj andinsulated therefrom is a column s. This column supports a platform 8which is made of metal, preferably copper. Upon this platform is fixed ascrew constituting .the screw 8 when the armature-lever is attracted bythe electromagnet, so that there can never be any electric communicationbetween the lever ,7' and the platform 8 at the moment when the armatureis attracted by the electromagnety. The insulating-block a is providedat the top with a metallic contact u made preferably of'platinum, andconnected with a flexible conductor a forming one of the terminals of abattery-cell c of low voltage. When the armature is released by theelectromagnet 7' and retracted by the spring 1", the contact 20 engagesthe end of the platinum screw t which passes through theinsulating-screw t, and which is electrically connected with one of theterminals of the coherer as explained below.

The plate 5, made of polished steel or other suitable metal rests uponthe support 8 and upon this plate 5 rests the tripod consisting of asmall plate 0 of brass or other conducting material and provided withthree legs a made of polished steel or other suitable material, the'extremities of these three legs at the point of contact with the plateI) being oxidized. Theoxidizationnormally prevents the passage of acurrent from the batterycell c in the circuit of which the coherer isinserted, but when the coherer is excited by electric oscillations theconductivity of the imperfect contact thus formed is greatly increased.The plate 0 is in electrical connection with the platinum screw 8 andtherefore in communication with one of the terminals of the cell 0whenever the lever 1' being released by the electromagnet f, isretracted. The other pole of the cell c is connected by a wire a withthe metallic support 8 upon which rests the polished steel plate 6.Along this wire are inserted in series an adjustable resistance g and arelay h. The latter at the moment when a current passes through thecircuit of the cell c closes the circuit of the local battery 2?,preferably of a potential of five or six volts, which sets in motion therecording apparatus 7'.

In order that the coherer may be shielded from the influence of externaldisturbances it is inclosed in a glass cylinder o. This cylinder isprovided internally with a ringo of insulating material, which ispolished internally and serves to limit the lateral play of the tripod.The cylinder also supports a crown-piece o made of insulating material,such as ivory. Upon this crown-piece rests an electromagnet 20 providedwith a central the magnet.

canal for the passage of the flexible conducting-wire connecting thetripod with the screw 6 This electromagnet w inserted in the circuit ofa small auxiliary battery 00 attracts the tripod and holds the sameelevated slightly above the polished steel plate 6 whenever a currentfrom the battery as is passing through For this purpose a soft iron ring0' is embedded into the upper partof the platform 0 and serves as anarmature. The conductor which is connected to the platform 0 consistspreferably of a wire of annealed silver, fixed as shown in Figs. 4 and 5by means of two semicylinders d between which it is pressed and uponwhich the nut d is fitted.

The mode of operation of the device shown in Fig. 5 is as follows: Whenthe apparatus is in a state of rest, the lever held by the spring fpresses the contact 2: against the screw 25 and the circuit of the cellc is kept open by the film of oxid upon the tips or hottoms of the legsa in contact with the plate 6. If, now, Hertzian waves from a distanceenergize the aerial the imperfect contacts between the plate a and thelegs a resting thereupon become temporarily conducting. The circuit ofthe cell c is thus virtually closed, the current from the celltraversing the relay it, thus causing the circuit of the local battery dto be closed. The current from'the battery z'energizes the electromagnetf causing it to attract the armature and drawing the contact member Q62away from the screw 6 thus breaking the circuit of the cell 6. Moreover,the lever f in its motion due to the attraction of the magnet, strikesagainst the screw 8 and gives the support 8 a slight shock which causesdecoherence of the imperfect contacts. The circuit of the cell c beingthus broken, the relay it is no longer traversed by a current, andtherefore the circuit of the local batter-yd is also broken. As aconsequence there is no current through the magnet 7' and the leverretracted by the spring returns to its original position, again pressingthe contact 162 against the screw i As the coherer has been decoheredthrough the shock of the lever against the screw .9 the circuit of thecell 6 remains open until the imperfect contacts are again affected bythe wave energy.

It will be noted that in my device the circuit of the cell c is brokenbefore the shock takes place. The shock therefore ensues after allinduced currents (such as arise in all bobbins, magnets, coils, (820.used in the Morse apparatus) have subsided, these currents beingproduced and given a chance to die down during the interval between thebreaking of the circuit and the shock of decoherence. The

closing of the circuit of the local battery 6 serves moreover, in theordinary way to throw into action the recording instrument which causesthe enrolling of the paper band and the impression thereupon of the longand short signs representing dots and dashes of the Morse alphabet.

In my device there is comparatively small play given to thearmature-lever, and in consequence a very rapid and certain transmissionof signals is effected. When it is desired'that the apparatus shall beoperated in the immediate vicinity of an oscillator the circuit of theauxiliary battery as is first closed so as to permit a current toenergize the electromagnet 20, which thereupon attracts the tripod andthus holds it clear of the plate I). In this way it is possible tooperate the receiver in the immediate vicinity of a transmitter throwingoff Hertzian waves. On account of this feature it is not necessary toremove thecoherer or to inclose it within a metal box in order to guardit against external influences. To' restore the instrument to itsreceiving condition, all that is required is that the circuit of thebattery as be broken so that thetripod immediately rests upon thepolished steel plate Z).

My improved apparatus may be varied in form and dimensions, and Ireserve the right to modify the details of construction to suit thedifferent applications.

I claim 1. In a wireless-telegraph receiver, the combination of acontact-point and contact-plate, both electrically connected in the mastand receiver circuits, and means for shifting the relative positions ofthe contact-point and contact-plate, so as to change the point ofengagement between the contact-plate and contactpoint.

2. In a wireless-telegraph receiver, the combination of a contact-point,an oxidized contact-plate, both electrically connected in the mast andreceiver circuits, and means for shifting the relative positions of thecontact-point and contact-plate so as to change the point of engagementbetween the contact-plate and contact-point.

3. In awireless-telegraph receiver the combination of an adjustablecontact-point with a longitudinally-movable contact-plate, bothelectrically connected in the mast and receiver circuits.

4:. A coherer, comprising a tray, means for adjusting the same, a plateof conducting material mounted within said tray, and a member forming animperfect contact with said plate.

The foregoing specification of my improved receiver for use in wirelesstelegraphy signed by me this 22d day of August, 1902.

EDOUARD BRAN LY.

Witnesses:

EDWARD P. MAOLEAN, MAURICE H. PIGUET.

